Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/30—Auxiliary operations or equipment
  • B29C64/386—Data acquisition or data processing for additive manufacturing
  • B29C64/393—Data acquisition or data processing for additive manufacturing for controlling or regulating additive manufacturing processes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/10—Processes of additive manufacturing
  • B29C64/106—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material
  • B29C64/124—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material using layers of liquid which are selectively solidified
  • B29C64/129—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material using layers of liquid which are selectively solidified characterised by the energy source therefor, e.g. by global irradiation combined with a mask
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/20—Apparatus for additive manufacturing; Details thereof or accessories therefor
  • B29C64/264—Arrangements for irradiation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/30—Auxiliary operations or equipment
  • B29C64/386—Data acquisition or data processing for additive manufacturing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y10/00—Processes of additive manufacturing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y50/00—Data acquisition or data processing for additive manufacturing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y50/00—Data acquisition or data processing for additive manufacturing
  • B33Y50/02—Data acquisition or data processing for additive manufacturing for controlling or regulating additive manufacturing processes

Definitions

• Title of the invention Process for printing a 3D object in a photoreactive composition, and printer suitable for implementing the process.
• the present application relates to an optical projection method suitable for printing in three dimensions (3D) in a volume of composition, as well as a 3D printer, using a nonlinear photochemical reaction induced by absorption of an energy supplied by a beam luminous to modify a photoreactive composition.
• the composition to be modified can be of various types.
• This composition may comprise a resin solidifying by polymerization or photo-crosslinking, a resin whose solubility properties are modified by photochemistry, proteins solidifying by photo-crosslinking, or metal salts solidifying by photo-reduction, or more generally any composition of which a physical (color, mechanical resistance, etc.) or chemical property is modified under the effect of a light signal.
• the excess of unmodified composition is dissolved by a suitable solvent after the modification.
• the modification of the composition is very localized because the yields of these photochemical reactions result from a nonlinear chemistry in irradiation or in fluence.
• the yields of these photochemical reactions induced by two-photon absorption are proportional to the square of the intensity of the laser source used, so that the modification of the composition is very localized.
• the nonlinearity is obtained by a mechanism of successive addition of photons, or by a threshold polymerization mechanism, or by a nonlinear chemical mechanism.
• the patent DI FR3023012 describes a 3D printer in which a laser beam of appropriate wavelength and power is focused successively at points of a reactive composition so that the volumes of the material located at the successive focusing points of the beam are modified by a photochemical reaction induced by two-photon absorption.
• the 3D printer comprises a laser source, a focusing lens and a composition tray to be modified resting on a table, said table being able to be moved according to directions orthogonal (X, Y directions) or parallel (Z axial direction) to the direction of propagation of a laser beam produced by the source.
• the laser beam is focused by the lens at a focal point located in the composition to be modified, the power of the beam decreasing as it moves away from the focal point.
• Focal volume is a volume of composition centered on a focal point, volume in which the energy of the light beam is sufficient to trigger the modification of the composition.
• the XYZ table is controlled so that the focal volume associated with the focal point of the beam is moved through the material to form voxels one after another until the volume of the 3D object to be printed has been solidified.
• the object is thus printed voxel by voxel, first in a plane orthogonal to the beam and defined by the directions X, Y then plane by plane along the direction Z.
• Dl proposes a solution for adjusting the size of the voxels during printing, thus making it possible to print successively very small voxels and larger voxels.
• This technical solution effectively makes it possible to accelerate the printing time of an object, but to the detriment of the resolution, in particular the axial resolution (along the Z axis), in the zones where the voxels are of larger size.
• the resolution in particular the axial resolution (along the Z axis)
• D2 "Hernandez-Cubero, O.
• Document D4 “Saha, Sourabh K., et al. "Scalable submicrometer additive manufacturing.” Science 366.6461 (2019): 105-109. describes the use of a space-time compression technique to achieve axial resolution when projecting a 2D image within the volume of a light-cured composition. This process requires the use of laser sources with femtosecond pulses and cannot be generalized to other photopolymerization light sources.
• the document D5 “Regehly, Martin, et al. "Xolography for linear volumetry 3D printing.” Nature 588.7839 (2020): 620-624. describes the use of a 3D light-curing technique based on the intersection of two light beams of different colors.
• the first beam projects, without axial resolution, the images to be polymerized into the resin tank. Propagation takes place without photochemical reaction up to the point of intersection with the second beam, a perpendicular sheet of light, which makes the photoinitiator molecules sensitive to the color of the first beam, and therefore makes it possible to obtain the axial resolution.
• This process is limited to the use of very specific photoinitiator molecules and radical polymerization resins. It cannot be generalized to the photo-chemical systems used in the state of the art.
• Document D6 “One-Step volumetry additive manufacturing of complex polymer structures” Shusteff, Maxim, Allison EM Browar, Brett E. Kelly, Johannes Henriksson, Todd H. Weisgraber, Robert M. Panas, Nicholas X. Fang, and Christopher M Spadaccini. "One-step volumetric additive manufacturing of complex polymer structures.” Science advances 3, no. 12 (2017): eaao5496, describes a new technology of projecting a solid 3D image into the nonlinear photoreactive composition tray, which can dramatically speed up print time.
• the projection takes place inside the composition tank itself and not on the surface, so that it is no longer necessary to move the table supporting the composition tray or to use a mobile sample holder in the composition tray.
• viscous photoreactive compositions insofar as the projection is carried out inside the volume of composition and where it is no longer necessary to move a sample holder in the composition tank.
• the fabrication of millimetric objects requires the orthogonal addition of three 2D images to obtain the axial resolution by nonlinear polymerization only at the places of addition of the projected irradiations. This makes the optical assembly complex and limits the 3D geometric shapes that can be printed.
• the present invention aims to overcome at least one of the drawbacks of the known printing methods and printers mentioned above, and in particular the problem of the loss of axial resolution in the luminous zones to be reacted by the image projection.
• the invention proposes a process for printing a 3D object in a volume of photoreactive composition, an object defined by a 3D image comprising a plurality of illuminated points, a printing process characterized in that it comprises the following steps, consisting of:
• each mosaic comprising a plurality of flat areas and each flat area comprising an illuminated point or a group of adjacent illuminated points , and
• the number of illuminated points and the distribution of the illuminated points in the said solid are adjusted so that the projection of the said mosaic in the composition volume, the luminous zone associated with the said solid generates the photoreacting a composition block having a desired axial resolution, and
• the flat areas of illuminated dots are distributed so that, during the projection of the said mosaic in the volume of composition, the composition does not photoreact between the luminous zones associated with the plurality of flat areas of the said mosaic.
• the desired axial resolution is a process parameter, chosen by the user, depending on the resolution he wishes to obtain for the printed physical object.
• solids can have various shapes, for example a compact shape, an elongated shape, a hollow shape, etc.
• the resolution of a printed object is directly related to the resolution of the optical image projected into the composition for printing.
• the projection of a digital image comprising solid areas (or groups of illuminated dots) comprising a large number of illuminated dots results in practice in an optical image with low axial resolution, and results in a printed object with low axial resolution.
• the invention proposes to print the same object by successive projections of partial images (or mosaics) comprising solid areas each comprising a smaller number of illuminated points to maintain optimum axial resolution.
• the small flat areas have sufficient irradiations to polymerize only around their focal points, and their diffracted intensities are too low to trigger a parasitic polymerization reaction degrading the axial resolution, as will be better seen further on.
• the essential step ET2 of the invention thus aims to limit the size of the flat areas projected.
• the image of the object to be printed is a 3-dimensional image, and the mosaics and the solid areas in said mosaics are also in 3D.
• the method can comprise an initial step (ET1) consisting in cutting the 3D image of the 3D object into a series of 2D images representative of the object to be printed in parallel planes between them and perpendicular to the axial direction of image projection in the composition volume, and in that it also comprises the following steps ET2 to ET4, repeated for each 2D image and consisting of:
• This embodiment allows layer-by-layer printing of the 3D object directly in the composition volume, and not on the surface of the composition as is the case with conventional layer-by-layer stereolithography methods.
• moving the focal plane in the composition avoids moving the object being printed in the composition volume. It thus becomes possible to use viscous or even solid compositions. Also, it is no longer necessary to use reinforcements to maintain, during its movement in the composition, a fragile object being printed.
• the invention also proposes a printer suitable for the implementation of a printing method described above, printer comprising in particular:
• the printer also comprising means arranged to implement the printing method according to one of preceding claims, said means comprising a generator (15) of mosaic sequences arranged to extract from the image of the object to be printed a sequence of mosaics and supplying the sequence of mosaics to the projector for performing step ET3 of projection.
• the image projector is chosen with lateral and axial optical resolutions adapted to the lateral and axial resolutions desired for the object to be printed.
• FIG. 1 schematically presents a printer according to the invention
• FIG. 2 schematically presents an essential step of a printing process according to the invention
• FIG. 3 presents test results facilitating the understanding of the essential step of the invention.
• a digital image of a physical object to be printed is defined by a plurality of illuminated dots distributed in a matrix comprising illuminated dots and unlit dots, the illuminated dots defining the object to be printed.
• a flat object can be represented by a two-dimensional (2D) dot matrix, the dots of which are commonly called pixels.
• a three-dimensional (3D) solid object can be represented by a three-dimensional point matrix, a matrix whose points are commonly called voxels.
• adjacent By convention, we will use the adjective “adjacent” to talk about two elements that are side by side and that touch each other; for example, in an image or a matrix representing an image, adjacent points touch on one side.
• an axial direction Z is defined as being a direction of projection of an image by a projector in a composition volume, and we define two lateral directions, X, Y, perpendicular to each other and perpendicular to the axial direction Z (see the reference figure 1).
• volume of composition is meant conventionally the contents of a container containing said composition, the volume of composition being delimited by the edges of the container.
• projection in a composition volume we mean a projection of an image inside the composition volume, and not a projection under the surface of the composition volume, as is commonly carried out according to conventional methods of layer-by-layer printing (stereolithography).
• a "solid” comprises a lit point or a group of adjacent lit points in which each lit point is adjacent to at least one other lit point of the same group.
• the dimension of a compact solid corresponds to its mean diameter
• the dimension of an elongated solid corresponds to its mean width.
• a spacing between two flat areas is a measured spacing (in millimeters, micrometers, nanometers, etc.) between an illuminated point located on one edge of one of the areas and an illuminated point located on an edge of the other of the areas.
• the distance between two solids is the minimum value of the spacing between two solids.
• luminous area is meant an illuminated area in the composition during the projection of a solid area of illuminated dots, where the light intensity is sufficient to generate a reaction of the composition.
• a luminous zone is generally larger than a zone in which a solid color is projected, as will be seen later in the examples of FIGS. 3 and 4, due to the propagation of the light beam beyond the projection zone.
• a mosaic is a partial digital image of the global digital image of a real object; a mosaic is extracted from a (complete) image of said object; a mosaic is of the same size, in terms of number of light points, as the digital image from which the mosaic is extracted; a mosaic includes only part of the illuminated points of the image from which the mosaic is extracted.
• optical resolution also called optical "axial length”
• optical "lateral resolution” of a light beam is the distance, in a lateral direction perpendicular to the direction of propagation, between two opposite points of a peak of maximum intensity which correspond to half of the maximum intensity.
• the “resolution of the photoreaction” is determined by the optical resolution of the light beam generating the photoreaction; it can be smaller or larger than the optical resolution of the light beam, depending on the type of composition and the conditions of irradiation above the minimum irradiation necessary for the photoreaction.
• the invention relates to the printing of 3D objects by projection of images in a volume of photoreactive composition, the modification of the composition of which is localized in the places of intense irradiation.
• the invention more specifically proposes a method for printing a 3D object in a volume of photoreactive composition, an object defined by a 3D image comprising a plurality of illuminated points.
• the printing process according to the invention comprises the following steps, consisting of:
• each mosaic comprising a plurality of flat areas and each flat area comprising an illuminated point or a group of adjacent illuminated points , and
• each mosaic in the composition volume, a plurality of zones luminous zones, each luminous zone corresponding to a flat area of the projected mosaic and each luminous zone being adapted to generate a photoreaction of an associated composition block.
• a solid can be two-dimensional (X, Y) or three-dimensional (X, Y, Z), depending on whether the mosaic that contains the solid is two-dimensional or three-dimensional.
• FIG. 3 shows the influence of the dimensions of the solid tints on the optical resolution necessary to obtain the axial resolution of the transformed composition block after projection of a solid tint image.
• Figures 3a, 3b represent the XY projections
• Figures 3ay, 3by represent the YZ projections
• Figures 3az, 3bz represent the XZ projections of the images obtained with a CMOS camera at different axial positions around the XY focal plane in which the images are projected.
• FIG. 3a shows an optical image comprising a single luminous zone resulting from the projection of a digital image comprising a single square solid area.
• the luminous zone corresponding to the solid area, of dimension 20 pm * 20 pm, is well delimited in the X,Y plane of projection (fig 3a), it spreads out on the other hand very widely in the YZ plane (fig. 3ay) as in the X,Z plane (fig. 3az) on either side of the focal plane in the Z axial direction and in very diffracted directions with respect to the Z axial direction.
• the optical axial resolution is 22 pm whereas the axial resolution of an optical solid with a single light point is 0.5 ⁇ m.
• FIG. 3b shows an optical image comprising luminous zones resulting from the projection of a digital image comprising a plurality of smaller square flat areas, fairly distant from each other; the distance between two luminous zones is 10 ⁇ m in the X, Y plane of projection.
• FIGS. 4 show the influence of the distance between flat tints each comprising an illuminated point on the luminous zones resulting from the projection of said flat tints, and therefore the influence of said distance on the reaction of the illuminated composition.
• the tests are carried out here with the same optical projection system as that of the tests presented in fig 3.
• Figures 4 are results of projection tests of a digital image comprising a plurality of equidistant areas, the projections of the areas having dimensions of 0.25 ⁇ m * 0.25 ⁇ m, in the X,Y projection plane, and dimensions of 0.5 ⁇ m in Z. the diffraction limit, that is to say with perfect focusing, imposed by the characteristics of the optical system used.
• the flat areas When the flat areas are separated by a distance of 2 ⁇ m from each other in the projection plane, the light areas they generate are very sharp and distinct from each other, both in the projection focal plane (fig. 4a) than along the axial plane X Z (fig 4az). Between the luminous zones, the luminous intensity is weak and insufficient to cause a modification of the composition.
• the flat areas When the flat areas are only separated by a distance of 0.8 ⁇ m from each other in the projection plane, the light areas they generate are not very sharp and not very distinct from each other in the XY projection plane (fig. 4b).
• the light zones In the axial direction Z, in the plane XZ (FIG. 4bz) and more generally in any plane parallel to the axial direction, the light zones spread out to the point of overlapping.
• the resulting energy can become sufficient to trigger a reaction of the composition. This results in a strong degradation of the axial resolution, as well as an undesired reaction of the composition between the flat areas where the beams of light overlap.
• the printing time is reduced by carrying out the steps ET2 and ET3 described above, which make it possible, from a breakdown into mosaics, partial images of the object to be printed, to simultaneously print pluralities of illuminated dots , instead of printing them one by one, which greatly speeds up printing.
• the axial resolution desired for the printed object is maintained by an appropriate distribution of the illuminated points in the mosaics and in the flat areas of the mosaics:
• the number of lit points and the distribution of illuminated points in the said flat area are adjusted so that, during the projection of the said mosaic in the composition volume, the luminous zone associated with the said flat area generates the photoreaction of a composition block having a desired axial resolution, and
• the flat areas of illuminated dots are distributed so that, during the projection of the said mosaic in the volume of composition, the composition does not photoreact between the luminous zones associated with the plurality of flat areas of the said mosaic.
• the number of lit points and the distribution of the lit points in the solid must be optimized.
• the number of illuminated points must be as large as possible to project as few mosaics as possible to print the complete object.
• the number of illuminated points must be limited and the distribution of illuminated points in a solid area must be optimized to maintain the desired axial resolution.
• the distribution of the lit points is materialized by the shape of the solid.
• the flat areas must be distributed in an optimized way.
• the distance between two flat areas must be minimized so that the number of illuminated points in a mosaic is as large as possible.
• the distance between two flat areas must be sufficient so that the composition does not react between two flat areas.
• Tests carried out under the test conditions presented in FIG. 3 and 4 show that, in a mosaic, flat areas having a dimension less than the desired axial resolution and preferably twice as small, give good results in terms of axial resolution.
• a compact shape for example a disc, a solid ball, a square, a cube, .etc. ; , for the purposes of the invention, it is considered that the dimension of such a solid is its average diameter
• an elongated shape for example an elliptical shape, an oblong shape, a cylinder, a bar, etc. ; , for the purposes of the invention, it is considered that the dimension of such a flat area is its average width
• a hollow shape for example a ring, a hollow sphere, a hollow cylinder, a hollow rectangle...
• the method according to the invention can be used to produce an object to be printed having macroscopic properties and having a desired lateral (XY) and/or axial (Z) resolution of the details which can be greater than 10 ⁇ m.
• the method can also be used to produce a printable object having microscopic properties with a desired lateral (XY) and/or axial (Z) resolution of detail which may be less than 10 ⁇ m.
• FIG. 2 shows, by way of simple example, the decomposition of an initial 2D image into a sequence of four 2D mosaics, the 2D image and the mosaics comprising 24*24 pixels (2D luminous points).
• the solid areas of the initial 2D image include 2*10 pixels
• the decomposition is such that the solid areas in the mosaics include at most 2*2 lit points.
• the decomposition according to the invention of images into mosaic sequences applies in a similar way to the decomposition of a 3D image representing a 3D object and defined by a three-dimensional matrix.
• a breakdown into four mosaics only makes it possible to obtain mosaics comprising flat areas comprising at most 4 lit points.
• larger images for example images of microscopic or macroscopic images defined by a matrix of 10000* 10000 pixels (in 2D) or by a matrix of 10000*10000*10000 voxels (in 3D)
• the number of mosaics in a sequence can quickly become large, even if flat areas comprising more than 1 lit point are acceptable.
• the number of mosaics will thus depend in practice on the density of the object to be printed or said, otherwise, the number of illuminated dots and the size of the initial solids in the initial image representing the object to be printed, and the desired resolution for the printed object.
• the step ET2 of extracting the sequence of mosaics can be carried out by trial and error, by choosing flat areas of simple shapes in line with the general shape or the local shapes of the object to be printed.
• step ET2 can be performed iteratively.
• a first version comprising alternately an illuminated point and an extinguished point can be tested with the composition to be modified and the associated optical means.
• turning points off or on ET22.
• steps ET21 and ET22 until a first satisfactory mosaic is obtained. Then repeat steps ET21 and ET22 for the following mosaics.
• the distance between solids and the distribution of solids in each mosaic, as well as the number and distribution of illuminated dots in each solid of a mosaic according to the desired axial resolution for the object to be printed must be characterized by tests with the projection means and the photoreactive composition chosen.
• tests carried out under the material conditions (projection means and choice of composition) of the experiment described in document D2 show that the axial resolution of a spot (modified composition element) obtained by holographic projection is equal at 1.6 times the diameter of the projected solid.
• an axial resolution equal to 16 ⁇ m, 8 ⁇ m or 1.6 ⁇ m
• the maximum dimension of an isotropic solid is chosen equal to 10 ⁇ m, 5 ⁇ m or 1 ⁇ m.
• each illuminated point of the image of the object is present in at least one solid area of a mosaic; the successive projection of each of the mosaics of the mosaic sequence thus makes it possible to constitute the entire object in the volume of composition. If each lit point is present in a single mosaic dataset, all points will be projected only once during the projection of the mosaic sequence; this makes it possible to obtain a printed object produced in a homogeneous material. A lit point present in several mosaics will be projected as many times, which amounts to increasing the projection time of said point, and therefore increasing the conversion rate of the composition; this makes it possible, for example, to locally reinforce a physical or chemical property of the printed object.
• At least one mosaic is projected several times, successively shifted along the axial direction and/or in a focal plane (XY) in the composition volume.
• This embodiment makes it possible, for example, to print parallel bars.
• first desired axial resolution with a first part of a mosaic and at least one second desired axial resolution with at least a second part of said mosaic.
• the mosaics of the sequence of mosaics can each be projected for an identical time, necessary for the reaction of the composition. This makes it possible, for example, to produce an object in a substantially homogeneous material.
• the mosaics of the sequence of mosaics are projected for different exposure times; this makes it possible, for example, to locally refine the mechanical properties of an object.
• a method according to the invention comprises an essential step ET2 of extracting a sequence of mosaics in an image of an object to be printing, and a step ET3 of projecting said sequence of mosaics into the volume of photoreactive composition.
• the image to be projected and the mosaics are also in 2D.
• the mosaics are projected successively in the same focal plane (perpendicular to the axial direction) in the composition volume inside the composition tray so that the object is formed in the composition volume as the projecting mosaics.
• the image of the object to be printed is a 3D image and the mosaics and the flat areas in the mosaics, obtained during step ET2, are also in 3D.
• 3D mosaics are projected, either as a real or holographic 3D image, into the composition volume within the composition so that the object forms in 3D within the composition volume as the projecting mosaics.
• the printing of a 3D object is carried out layer by layer by the successive printing of adjacent 2D layers.
• the method according to the invention comprises an initial step (ET1) consisting in cutting the 3D image of the 3D object into a series of 2D images representative of the object to be printed in parallel planes between them and perpendicular to the axial direction of image projection in the composition volume, and it comprises the following steps ET2 to ET4, repeated for each 2D image and consisting in
• step ET4 of displacement of the focal plane is carried out by spatial modulation of an initial light beam produced by a light source of the projector used to carry out step ET3 of projection, the modulated beam integrating information relative to the position of the focal plane.
• the invention also proposes a printer for implementing the method described above, the principle of which is shown in a deliberately simplified manner in FIG. 1.
• the printer comprises:
• a tank 2 containing a volume of a photoreactive composition for example a photopolymerizable resin solidifying by a nonlinear polymerization mechanism
• an image projector 10 arranged to project a focused image, with a desired axial resolution, in the composition volume.
• the photoreactive composition is for example a photopolymerizable resin solidifying by a multiphoton absorption process, by a photon addition mechanism, by a threshold polymerization mechanism, or by a nonlinear chemistry mechanism.
• the printer according to the invention also comprises means arranged to implement the printing method as described above, in particular a generator (15) of mosaic sequences arranged to extract from the image of the object to printing a sequence of mosaics and supplying the sequence of mosaics to the projector for carrying out step ET3 of projection.
• a generator (15) of mosaic sequences arranged to extract from the image of the object to printing a sequence of mosaics and supplying the sequence of mosaics to the projector for carrying out step ET3 of projection.
• the projector 10 projects an image into the composition and the illuminated areas react by forming all or part of the object to be printed.
• the projector 10 comprises:
• a light source (4) producing, for each mosaic to be projected, an initial beam having appropriate parameters to trigger a photoreaction of the composition, the said parameters comprising for example a power, a wavelength and/or an exposure time,
• a spatial light modulator (12) arranged to, from the initial beam and the mosaic to be projected, produce a beam to be projected by the optical device, and
• an optical imaging device (11) arranged to focus the beam to be projected in a focal plane associated with the mosaic to be projected.
• the means for implementing the printing process can also comprise cutting means, for cutting a 3D image into a series of 2D images representative of the object to be printed in planes parallel to each other and perpendicular to the axial direction. image projection in the composition volume.
• the slicing means supply the mosaic generator 15 one after the other with the 2D images of the series of 2D images resulting from the decomposition.
• the means for implementing the printing method according to the invention also comprise means for controlling the positioning of the focal plane.
• the composition tray 2 is placed on a motorized table 3 movable in axial translation in the direction of projection of the projector 10, and means for controlling the motorized table are arranged to provide said motorized table with a movement command signal in the axial direction or in a lateral direction (X, Y). The focal plane in the tray is thus moved by moving the tray.
• the composition tray 2 is placed on a fixed table, and projector control means are arranged to supply the projector with a control signal comprising an axial position of a focal plane.
• the distance between the tray and the projector remains fixed, but the focal plane is moved in the tray.
• the projector control means supply the imaging device 11 with the control signal comprising the axial position of the focal plane and the imaging device focuses the beam to be projected in the focal plane at the interior of the composition volume.
• the projector control means supply the modulator 12 with the control signal comprising the axial position of the focal plane and the modulator produces a phase-modulated beam to be projected incorporating information relating to the focal plane.
• the printer according to the invention can be an electro-opto-mechanical machine such as that conventionally used in a photoplotter, in a DLP 3D printer, in an LCD 3D printer, in a printer implementing a microstereolithography process or in a microscope; the machine is diverted from its usual use, and adapted and supplemented by the means of implementing the invention in particular: a generator of mosaic images 15, a projector 10 and means for controlling the electro-opto-mechanical machine and, if the table is mobile, means for controlling the mobile table.
• composition tray 2 and/or the optical imaging device 11 can be arranged with lateral displacement means (in the XY plane) to produce larger objects by the successive projection of several sequences of mosaics in the lateral plane .
• the invention proposes a 3D printing process and means for implementing said process, which in particular provide the following technical and economic benefits:

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Optics & Photonics (AREA)
• Health & Medical Sciences (AREA)
• Toxicology (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=76283810

Family Applications (1)

Country Status (4)

Families Citing this family (5)

Family Cites Families (6)

• 2021
  • 2021-02-09 FR FR2101233A patent/FR3119562B1/fr active Active
• 2022
  • 2022-02-09 EP EP22704913.7A patent/EP4291384A1/de active Pending
  • 2022-02-09 WO PCT/EP2022/053176 patent/WO2022171704A1/fr not_active Ceased
  • 2022-02-09 US US18/264,816 patent/US20240051233A1/en not_active Abandoned

Also Published As

Similar Documents

Legal Events